To make the case for more widespread use of sunburn-free testing, the European Commission recently funded a campaign during which the sun protection factor (SPF) and UVA protection factor of 74 sunscreen products (sunscreens as well as day creams) were tested in laboratory conditions (in vitro).
The results showed a high level of correlation between in vitro and in vivo testing, which supports the reliability of the former to verify SPF claims.
The in vitro test method (EN ISO 23675:2024) used was published in December 2024. It eliminates the need for exposing human volunteers to UV radiation, is cheaper than testing on humans and is faster. A hybrid method published at the same time, HDRS, uses human subjects, but does not cause harm. This testing campaign only compared the in vitro and conventional in vivo methods.
Another advantage of in vitro SPF testing is that the results are not affected by the presence of anti-inflammatory or soothing ingredients in some products.
Some anti-inflammatory or soothing ingredients may reduce or delay this reaction, leading to an artificially higher SPF number.
The limitation of the in vitro method is that sunscreen sticks and powders cannot currently be tested.
Manufacturers are advised, when testing their products to determine SPF and UVA, to prioritize testing that does not cause harm to human volunteers.
